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BIOLOGICAL PLANT SIZING Ing. Alberto Scaunich Slide 2 EXISTING PLANT (or available data flowrate EXISTING PLANT (or available data flowrate and pollutants concentration) Generally are available data for: FlowQ[m3/d] Pollutant concentration c[mg/l] Pollutant Load C[kg/d]= Q*c/1000 STATISTIC ELABORATION Slide 3 EXISTING PLANT (or available data flowrate EXISTING PLANT (or available data flowrate and pollutants concentration) When are available a lot of data, its better to eliminate single data (only flow or only concentration). Hence you proceed in statistic elaboration. At the end, when you have average values of flow and loads, calculate the value ratio: average load(concentration) average flow which generally is different from concentration average values and is more significant, representing the weighted average of concentrations. Slide 4 NOT EXISTING PLANT NOT EXISTING PLANT 1.MUNICIPAL WASTE WATER You have to refer your design to the SPECIFIC CONTRIBUTION PER CAPITA, which generally result prudential values. 2.INDUSTRIAL WASTE WATER You have to refer your design to the available SPECIFIC CONTRIBUTION PER UNIT OF PRODUCTS, adopting some security factors. Slide 5 POLLUTANTS BALANCE In biological plant sizing the ratio COD/BOD and BOD/TKN (or COD/TKN) are very important In biological plant sizing the ratio COD/BOD and BOD/TKN (or COD/TKN) are very important In Denitrification you need organic load to remove Nitrogen. assume: 3 kgBOD/kg(N-NO 3 ) DEN sizing oxidation 4 kgBOD/kg(N-NO 3 ) DEN sizing post-denitrification (methanol requirements) (methanol requirements) Calculate Pollutants balance for these following cases (to verify section sizing): M (BOD) + M(TKN) M(BOD) + M+2 (TKN) M+2 BOD) + M(TKN) Slide 6 NITROGEN BALANCE TKN in +(N-NO 2 ) in +(N-NO 3 ) in = TKN in +(N-NO 2 ) in +(N-NO 3 ) in = = TKN SED +(N-NO 3 ) DEN +TKN ox +TKN out +(N-NO 2 ) out +(N-NO 3 ) out Where: TKN in = inlet Nitrogen (organic ed ammonia) (N-NO 2 ) in = inlet Nitrogen (nitrite):generally absent (N-NO 3 ) in = inlet Nitrogen (nitrate):present only in industrial wastewater TKN SED = organic Nitrogen removed in primary sedimentation: 1015% TKN in TKN in (N-NO 3 ) DEN = nitrogen to remove by denitrification TKN ox = TKN removed by bacterial metabolism (5% BOD removed in biological treatment = 0,05 (BODi n Den BOD out ) TKN out = outlet Nitrogen (organic ed ammonia) - assume: 1 mg/l (N-NO 2 ) out = outlet Nitrogen (nitrite) - negligible (N-NO 3 ) out = outlet Nitrogen (nitrate) - project requirement(1015 mg/l) Normally you cant have in the same time significant values of (N-NH 3 ) out and (N-NO 3 ) out Slide 7 Slide 8 DENITRIFICATION DESIGN DENITRIFICATION VELOCITY (municipal effluents) ( D ) T = ( D ) 20 * T-20 Where: ( D ) T [gN-NO3/kgVSS*d] = Denitrification velocity:actual operative conditions (temperature = T); ( D ) 20 [gN-NO3/kgVSS*d] = Denitrification velocity: max value at T = 20 C, without any limiting factor; = Temperature correction coefficient (higher value, higher T dependence) = Temperature correction coefficient (higher value, higher T dependence) Slide 9 DENITRIFICATION VELOCITY DENITRIFICATION INTERNAL CARBON PRE-DEN Inizial velocity PRE-DEN Average vel. POST- DEN Average vel. VOCEUnit di misura Scaunich vecchio Scaunich attuale Forte influenza T Esercizio attuale Debole influenza T Organic fraction SSV/SST 0,7 Temperature correction coefficient 1,121,0651,2001,0801,030 Denitrification velocitya C20 gN-NO3/kgSSTxd 70,056,0504,070,750,4 a C18 gN-NO3/kgSSTxd 55,849,4350,060,647,5 a C16 gN-NO3/kgSSTxd 44,543,5243,152,044,8 a C14 gN-NO3/kgSSTxd 35,538,4168,844,642,2 a C12 gN-NO3/kgSSTxd 28,333,8117,238,239,8 a C10 gN-NO3/kgSSTxd 22,529,881,432,737,5 Denitrification velocitya C20 gN-NO3/kgSSVxd 100,080,0720,0101,072,0 a C18 gN-NO3/kgSSVxd 79,770,5500,086,667,9 a C16 gN-NO3/kgSSVxd 63,662,2347,274,264,0 a C14 gN-NO3/kgSSVxd 50,754,8241,163,660,3 a C12 gN-NO3/kgSSVxd 40,448,3167,454,656,8 a C10 gN-NO3/kgSSVxd 32,242,6116,346,853,6 Slide 10 DENITRIFICATION VOLUME CALCULATION (N-NO 3 ) DEN V = ------------------- ( D ) T * X ( D ) T * XWhere: V [m 3 ] =Minimum design Denitrification volume T [C] = Minimum design Temperature (N-NO 3 ) DEN [kg N-NO 3 /d] = nitrogen to remove by denitrification X [kgSSV/m 3 ]: = Volatile Suspended Solids concentration in biological basins (Denitrification Nitrification) Note:Its opportune to assure a minimum residential time of 34 h at the maximum flow, to give to mixed liquor enough time to reduce its O 2 content (DO concentration of 0,5 mg/l reduce denitrification efficiency to 10%) Slide 11 MIXED LIQUOR TO RECYCLE CALCULATION 1000 * (N-NO 3 ) DEN 1000 * (N-NO 3 ) DEN Q ML = ------------------------- - Q R 24 * N-NO 3 out 24 * N-NO 3 outWhere: Q ML [m 3 /h] = flowrate of recirculated Mixed Liquor Q R [m 3 /h] = return sludge flowrate (N-NO 3 ) DEN [kg N-NO 3 /d] = nitrogen to remove by denitrification N-NO 3 out [g/m 3 ] = concentration of nitrogen in outlet stream (design value) 1000= conversion factor (kg g) 24 =conversion factor (d h) Slide 12 MIXING - DENITRIFICATION Above 810 W/m 3 energy density is required(normal submersible mixers) Mixer rotation velocity must be chosen as low as possible (< 700 rpm) Slide 13 OXIDATION DESIGN PRELIMINARY SIZING BOD in V = --------------- X * F/M X * F/MWhere: BOD in [kgBOD/d] = Inlet BOD, coming from Denitrification X [kgSST/m 3 ] = Total Suspended Solids concentration in biological basins (Denitrification Nitrification): Values: 46 SSV/SST= Organic fraction: typical = 0,7 F/M [kgBOD/kgSST*d] = Ratio Food/Mass: Typical values range - extended aeration 0,075 (0,060,09) - nitrification (according T) 0,15 (0,120,18) - carbon removal only ( =85-90%) 0,25 (0,20,35) Slide 14 OXIDATION DESIGN NITRIFICATION VERIFING Where: ( n ) T = Nitrification velocity: actual operative conditions (temperature = T [gTKN/kgSSV/d]; ( n ) 20 = Nitrification velocity: max value at T = 20 C, without any limiting factor; [gTKN/kgSSV/d]; = Temperature correction coefficient; = Temperature correction coefficient; K TKN, K O = semisaturation constants, relating to TKN and DO [mg/l]; TKN, O.D.= TKN and Oxygen concentrations in biological basins [mg/l] Slide 15 OXIDATION DESIGN NITRIFICATION VERIFING Slide 16 OXIDATION DESIGN CALCULATION OF NITRIFICANT BACTERIA FRACTION Where: y N = nitrificant bacteria cellular yield coefficient [kgSSV/kg/TKN] y = heterotrophic bacteria cellular yield coefficient [gSSV/gBOD] S0 = inlet organic matter [mg/l] Se = outlet organic matter [mg/l] TKN0 = inlet TKN [mg/l] TKNe = outlet TKN [mg/l] y/yN = 4,72 (Bonomo, 2008) Slide 17 OXIDATION DESIGN NITRIFICATION VOLUME CALCULATION Where: x = Total Suspended Solids concentration in biological basins [kgSST/m3] X N = Total nitrificant bacteria in nitrification basins [kgSST] Slide 18 OXIDATION DESIGN RETURN SLUDGE FLOWRATE Where: x r = Total Suspended Solids concentration in return sludge [kgSST/m3] Slide 19 OXIDATION DESIGN RETURN SLUDGE FLOWRATE IMHOFF CONE (Q + Q r )V a = Q r V r Q r V a Q r V a -------------- = --------------- Q V r - V a Q V r - V a If V r = 1 l/l Q r V a Q r V a -------------- = --------------- Q 1 - V a Q 1 - V a Slide 20 OXIDATION DESIGN RETURN SLUDGE FLOWRATE SVI (sludge volume index) Where: x = Total Suspended Solids concentration in biological basins [g/l] Q r x Q r x -------------- = --------------- Q 1000/SVI - x Q 1000/SVI - x Imhoff cone 30 min [ml/l] or [cc/l] Imhoff Imhoff SVI = --------------- x x Slide 21 OXIDATION DESIGN EXCESS SLUDGE FLOWRATE CALCULATION Slide 22 OXIDATION DESIGN ACTUAL OXYGEN REQUIREMENTS (AOR) & STANDARD OXYGEN REQUIREMENTS (SOR) Where: a = Carbon removal coefficient = 0,5 kgO2/kgBOD b = Endogenous respiration coefficient = 0,08 kgO2/kgSST/d N da nitrificare = N to remove in nitrification [kgN-NH4/d] 2,86 KgO2/KgN DEN = Oxygen recovery Slide 23 OXIDATION DESIGN ACTUAL OXYGEN REQUIREMENTS (AOR) & STANDARD OXYGEN REQUIREMENTS (SOR) Where: a = rapporto tra il coefficiente di trasferimento relativo al liquido reale a 20C e quello relativo alle condizioni standard, fissato pari a 0,70; a = rapporto tra il coefficiente di trasferimento relativo al liquido reale a 20C e quello relativo alle condizioni standard, fissato pari a 0,70; b = rapporto tra la concentrazione di ossigeno a saturazione nel liquido reale in condizioni di esercizio e quella in acqua pulita in condizioni di esercizio; C s,T = concentrazione di ossigeno a saturazione in acqua pulita alla temperatura di esercizio T; C w,T = concentrazione di ossigeno nel liquido reale alle condizioni di esercizio, fissata pari a 2 mg/l; C s,* = concentrazione di saturazione in acqua pulita in condizioni standard (20 C); T = Temperatura nelle condizioni di esercizio Slide 24 OXIDATION DESIGN AIR DEMAND Where: 24 = days hours; 24 = days hours; 0,28 = Kg O 2 / mc air in standard conditions (20C 0 m a.s.l.); h = transfer efficiency O 2 = 5% / m depth. Slide 25 SEDIMENTATION DESIGN Hydraulic head (mc/mqxh) Hydraulic head (mc/mqxh) C i =Q/A 0,20 0,30 0,20 0,30 - Q (mc/h), flowrate - Q (mc/h), flowrate - A (mq), area - A (mq), area Solid load Solid load (kg SST/mqxd) (kg SST/mqxd) Cs = G/A < 5 a Q 24 < 5 a Q 24Slide 26 BIOLOGICAL TREATMENTS WASTEWATER TREATMENT PLANT Slide 27 PIATTELLI PER AERAZIONE AD ALTA EFFICIENZA BIOLOGICAL TREATMENTS Slide 28 PIATTELLI PER AERAZIONE AD ALTA EFFICIENZA BIOLOGICAL TREATMENTS Slide 29 PIATTELLI PER AERAZIONE AD ALTA EFFICIENZA BIOLOGICAL TREATMENTS Slide 30 PIATTELLI PER AERAZIONE AD ALTA EFFICIENZA BIOLOGICAL TREATMENTS Slide 31 DENITRIFICAZIONE - OSSIDAZIONE BIOLOGICAL TREATMENTS Slide 32 OSSIDAZIONE E TUBAZIONI RICIRCOLO BIOLOGICAL TREATMENTS Slide 33 OSSIDAZIONE Slide 34 OSSIDAZIONE Slide 35 DENITRIFICAZIONE - OSSIDAZIONE BIOLOGICAL TREATMENTS Slide 36 OSSIDAZIONE - OKI BIOLOGICAL TREATMENTS Slide 37 OSSIDAZIONE Slide 38 OSSIDAZIONE - OKI BIOLOGICAL TREATMENTS Slide 39 OSSIDAZIONE A BOLLE MEDIE BIOLOGICAL TREATMENTS Slide 40 BIODISCHI Slide 41 SEDIMENTAZIONE Slide 42 SEDIMENTAZIONE Slide 43 SEDIMENTAZIONE CARROPONTE ASPIRATO BIOLOGICAL TREATMENTS Slide 44 SEDIMENTAZIONE Slide 45 SEDIMENTAZIONE Slide 46 SEDIMENTAZIONE Slide 47 SEDIMENTAZIONE